A significant percentage of OB stars are runaways , so we should expect a similar percentage of their evolved descendants to also be runaways .
However , recognizing such stars presents its own set of challenges , as these older , more evolved stars will have drifted further from their birthplace , and thus their velocities might not be obviously peculiar .
Several Galactic red supergiants ( RSGs ) have been described as likely runaways , based upon the existence of bow shocks , including Betelgeuse .
Here we announce the discovery of a runaway RSG in M31 , based upon a 300 km s ^ { -1 } discrepancy with M31 ’ s kinematics .
The star is found about 21′ ( 4.6Â kpc ) from the plane of the disk , but this separation is consistent with its velocity and likely age ( \sim 10Â Myr ) .
The star , J004330.06+405258.4 , is an M2Â I , with M _ { V } = -5.7 , \log L / L _ { \odot } =4.76 , an effective temperature of 3700Â K , and an inferred mass of 12-15 M _ { \odot } .
The star may be a high-mass analog of the hypervelocity stars , given that its peculiar space velocity is probably 400-450 km s ^ { -1 } , comparable to the escape speed from M31 ’ s disk .